Find the maximum value from JSON data in Scala - json

Question

I am very new to programming in Scala. I am writing a test program to get maximum value from JSON data. I have following code:
import scala.io.Source
import scala.util.parsing.json._
object jsonParsing{
//Id int `json:"id"`
//Price int `json:"price"`
def main(args: Array[String]): Unit = {
val file_name = "jsonData.txt"
val json_string = scala.io.Source.fromFile("jsonData.txt").getLines.mkString
val json_arr = json_string.split(",")
json_arr.foreach {println}
}
}
The json_arr.foreach {println} prints following data:
[{ "id":1
"price":4629}
{ "id":2
"price":7126}
{ "id":3
"price":8862}
{ "id":4
"price":8999}
{ "id":5
"price":1095}]
I am stuck at the part of figuring out how to find the maximum price from such JSON data? That is, in this case the output should be '8999'.

Answer 1

you can try something like this below:
package com.x.x.integration.commons
import collection.immutable.IndexedSeq
import com.google.gson.Gson
import com.google.gson.JsonObject
import com.google.gson.JsonParser
case class wrapperObject(val json_string: Array[MyJsonObject])
case class MyJsonObject(val id:Int ,val price:Int)
object Demo {
val gson = new Gson()
def main(args: Array[String])={
val json_string = scala.io.Source.fromFile("jsonData.txt").getLines.mkString
//val json_string= """{"json_string":[{"id":1,"price":4629},{"id":2,"price":7126},{"id":3,"price":8862},{"id":4,"price":8999},{"id":5,"price":1095}]}"""
val jsonStringAsObject= new JsonParser().parse(json_string).getAsJsonObject
val objectThatYouCanPlayWith:wrapperObject = gson.fromJson(jsonStringAsObject, classOf[wrapperObject])
var maxPrice:Int = 0
for(i <- objectThatYouCanPlayWith.json_string if i.price>maxPrice)
{
maxPrice= i.price
}
println(maxPrice)
}
}
check if it helps you

Answer 2

I also recommend to use Json4s or playJson.
But you could do without any libraries as such.
val json = """[{"id":1,"price":100},{"id":2, "price": 200}]"""
val priceRegex = """"price"\s*:\s*(\d+)""".r
val maxPrice = priceRegex.findAllIn(json).map({
case priceRegex(price) => price.toInt
}).max
println(maxPrice) // print 200

Answer 3

Although Play JSON is handy, you could use Regex as well.
import scala.io.Source
import scala.util.matching.Regex._
val jsonString = Source
.fromFile("jsonData.txt")
.getLines.mkString.split(",")
var maxPrice = 0
jsonString.foreach(each => {
val price: Option[Match] = ("\"price\":(\\d+)").r.findFirstMatchIn(each)
if (price.isDefined) {
maxPrice = Math.max(maxPrice, price.get.group(1).toInt)
}
})